Projectile

ABSTRACT

A projectile includes a head portion, a middle portion and a tail portion. The middle portion is disposed between the head portion and the tail portion. A recess is defined from a terminal end of the tail portion extending into the middle portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Korean Patent Application Nos. 10-2016-0141881, filed Oct. 28, 2016, 10-2016-0145967, filed Nov. 3, 2016, and 10-2017-0049955, filed Apr. 18, 2017, the entirety of which is incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates to a projectile, and more particularly, a projectile capable of implementing a long effective range, a high accuracy of hitting, and strong destructive power.

There has been an interest in bullets or shells capable of implementing a long effective range, a high accuracy of hitting, and strong destructive power. In addition, demands for lightweight bullets or shells are also increasing.

In this regard, the present disclosure was made in light of the foregoing, and it is desirable to provide a lightweight projectile capable of implementing a long effective range, a high accuracy of hitting, and strong destructive power.

BRIEF SUMMARY

In an example, a projectile includes a head portion, a middle portion and a tail portion. The middle portion is disposed between the head portion and the tail portion. A recess is defined from a terminal end of the tail portion extending into the middle portion. A length that the recess extends into the middle portion is in the range of L/11 to L/22 where L is a length of the projectile.

In another example, a projectile includes a head portion, a middle portion and a tail portion. The middle portion is disposed between the head portion and the tail portion. A recess is defined from a terminal end of the tail portion extending into the middle portion. A center of gravity of the projectile is disposed between a midpoint of the projectile and a terminal end of the head portion.

In another example, a projectile includes a head portion, a middle portion and a tail portion. The head portion includes a first region having a concave profile. The middle portion is disposed between the head portion and the tail portion. A recess is defined from a terminal end of the tail portion extending into the middle portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an exemplary projectile shown in two rotated positions.

FIG. 2A is a side view of an exemplary projectile.

FIG. 2B is a bottom view of the exemplary projectile of FIG. 2A showing grooves of a first exemplary shape.

FIG. 2C is a bottom view of the exemplary projectile of FIG. 2A showing grooves of a second exemplary shape.

FIG. 2D is a bottom view of the exemplary projectile of FIG. 2A showing grooves of a third exemplary shape.

FIG. 3A is a perspective view of an exemplary projectile exiting a muzzle.

FIG. 3B is a perspective view of an exemplary projectile exiting a muzzle.

FIG. 4 is a perspective view of an exemplary projectile exiting a muzzle.

FIG. 5A is a photograph of a projectile expelled from a muzzle.

FIG. 5B is a photograph of a projectile expelled from a muzzle a period of time after FIG. 5A.

FIG. 5C is a photograph of a projectile expelled from a muzzle a period of time after FIG. 5B.

FIG. 6A is a photograph of a projectile expelled from a muzzle.

FIG. 6B is a photograph of a projectile expelled from a muzzle a period of time after FIG. 6A.

FIG. 6C is a photograph of a projectile expelled from a muzzle a period of time after FIG. 6B.

FIG. 7 is a rear perspective view of an exemplary projectile.

FIG. 8 is a side view of a projectile without grooves.

FIG. 9A is a diagram illustrating a trajectory of a projectile.

FIG. 9B is a diagram illustrating a trajectory of a projectile.

FIG. 10 is a side view of an exemplary projectile.

FIG. 11 is a diagram illustrating an exploded and internal of an exemplary projectile.

FIG. 12 is a diagram illustrating an exemplary jacketed projectile.

FIG. 13A is a cutaway and exploded view of an exemplary projectile.

FIG. 13B is a cutaway and exploded view of an exemplary projectile.

FIG. 13C is a cutaway and exploded view of an exemplary projectile.

FIG. 13D is a cutaway and exploded view of an exemplary projectile.

FIG. 14A is a cutaway and exploded view of an exemplary projectile.

FIG. 14B is a cutaway and exploded view of an exemplary projectile.

FIG. 14C is a cutaway and exploded view of an exemplary projectile.

FIG. 14D is a cutaway and exploded view of an exemplary projectile.

FIG. 15A is a perspective view of an exemplary projectile core.

FIG. 15B is a perspective view of an exemplary projectile core.

FIG. 16 is a side view of an exemplary projectile.

FIG. 17 is a partial side view of an exemplary projectile head.

FIG. 18A is a side view of an exemplary projectile illustrating a supercavitation effect.

FIG. 18B is a side view of an exemplary projectile illustrating a supercavitation effect.

FIG. 19 is a partial side view of an exemplary projectile head.

FIG. 20 is a partial side view of an exemplary projectile head.

FIG. 21 is a side view of an exemplary projectile.

FIG. 22 is a diagram of an exemplary artillery projectile.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

The present disclosure applies, for example, to bullets having relatively small calibers for use in small guns such as pistols, rifles, and machineguns and shells having relatively large calibers for use in large guns or artillery weapons such as cannons, howitzers, mortars, and weapons installed in tanks, fighters, battleships, and submarines. In this specification, references to projectiles may include bullets, shells, and substances expelled from weapons using an propellant. The present disclosure may also apply to projectiles that are expelled from weapons such as railguns using a magnetic field in addition to weapons using gunpowder as propellant.

FIG. 1 is a diagram illustrating an external appearance of a projectile according to a first embodiment of the present disclosure. The projectile 100 includes a head portion 110, a middle portion 120, and a tail portion 130.

The head portion 110 has an ogive shape with a substantially streamlined nose to reduce air resistance or the drag of air.

The middle portion 120 may be a full diameter straight section. The caliber corresponds to the diameter of the middle portion 120. The middle portion 120 may include a driving band 122 formed on an outer surface thereof near the tail portion 130. The driving band 122 limits or prevents the forward loss of gas around the projectile 100 in cooperation with the rifling of the barrel and is made of, for example, copper or a gilding metal.

The tail portion 130 includes a boat tail shape whose diameter gradually decreases. The tail portion 130 includes a plurality of grooves 132. The plurality of grooves 132 may be symmetrically formed at regular intervals. Each of the grooves 132 extend from a part of the middle portion 120 up to the bottom of the projectile 100 and may be substantially in a straight line form. It should be noted that if the groove 132 has a helical shape, the projectile 100 may not move forward and deviate from the target, and thus the accuracy of hitting of the projectile 100 is remarkably lowered. In some examples, only some of the grooves 132 which are symmetrically arranged may extend from a part of the middle portion 120 up to the bottom of the projectile 100. As will be described later, in some examples, a length Lg of the groove 132 is larger than a length La of the tail portion 130. As illustrated in FIGS. 2B-2D, the groove 132 may have various shapes, and for example, the groove 132 may be a semi-circular, semi-elliptical, or semi-oval cross-sectional shape or may have a polygonal cross-sectional shape such as a rectangular or triangular cross-sectional shape.

In the groove 132, a width of an upstream part 132 a and a width of a downstream part 132 b may be substantially equal or may be different. In the example of FIG. 1, the width of the upstream part 132 a is smaller than the width of a downstream part 132 b. Similarly, a depth of an upstream part 132 a and a depth of a downstream part 132 b may be substantially equal or may be different. Preferably, the depth of the groove 132 gradually increases downwards. A cross-sectional shape of the upstream part 132 and a cross-sectional shape of the downstream part 132 b may substantially coincide or may be different. For example, the cross-sectional shape of the upstream part 132 may coincide with the cross-sectional shape of the downstream part 132 b, but the width of the upstream part 132 a may be different from the width of the downstream part 132 b. For example, in a case in which the upstream part 132 and the downstream part 132 b have a semi-circular shape, it is preferable that a radius value of the cross section of the upstream part 132 be substantially equal to a radius value of the cross-section of the downstream part 132 b. Similarly, in a case in which the upstream part 132 and the downstream part 132 b have an inverted triangle, it is preferable that an internal angle of the inverted triangle of the cross section of the upstream part 132 be substantially equal to an internal angle of the inverted triangle of cross section of the downstream part 132 b.

Here, for the sake of simplicity of description, the description will proceed with an example in which the upstream part 132 a and the downstream part 132 b have the semi-circular cross section, the width of the groove 132 gradually increases downwards, and the depth of the groove 132 gradually increases downwards.

As described above, the length Lg of the groove 132 is larger than the length Lt of the tail portion 130. In this case, when the projectile 100 is expelled from the muzzle, a certain amount of gas is uniformly discharged through the groove 132 exposed from the muzzle as illustrated in FIG. 3, and thus a yaw angle θy of the projectile 100 is reduced at an early stage as illustrated in FIG. 4, and the projectile 100 flies stably, leading to a long effective range and a high accuracy of hitting.

However, in the case of the projectile of the related art, when the projectile is expelled from the muzzle, the gas is non-uniformly discharged, and thus the yaw angle of the projectile is large, and the projectile flies unstably.

FIGS. 5A-5C are photographs illustrating firing of a conventional projectile, and FIGS. 6A-6C are photographs illustrating firing the projectile 100 of the present disclosure. As can be seen from FIGS. 6A and 6B, when the projectile 100 is expelled from the muzzle, the gas may be uniformly discharged through the groove 132 exposed from the muzzle, and the projectile 100 stably flies with a small yaw angle, as compared with the projectile of the related art.

Preferably, the length Lt of the tail portion 130 is ⅛ to ½ of the length (L) of the projectile 100, and the length Lg of the groove 132 is larger than the length of the tail portion 130 by Ld. Preferable dimensions are:

Lt=L/8 to L/2

Lg=(L/8 to L/2)+(L/11 to L/22)

Ld=Lg−Lt=L/11 to L/22

In FIG. 1, θt indicates an angle of the tail portion 132 relative to the outer surface of the middle portion 120 (hereinafter referred to as a “tail angle”), and θg indicates an angle of the groove 132 relative to the outer surface of the middle portion 120 (hereinafter referred to as a “groove angle”). That is, θg is an angle between an imaginary line obtained by connecting the deepest part (for example, a center point Pdc) of the groove 132 with a center point Puc of the upstream part 132 a and an imaginary line extended from the outer surface of the middle portion 120. The groove angle θg is preferably set to satisfy the following Formula (1):

tan tg=(2×C)/3)/{(L/8 to L/2)+(L/11 to L/22)) to (C/2)/{(L/8 to L/2)+(L/11 to L/22)},  (1)

where L indicates the length of the projectile 100, and C indicates the diameter of the projectile 100.

A difference between the groove angle θg and the tail angle θt depends on the diameter of the projectile 100 and is in a range of preferably 5° to 30°, and more preferably 10° to 20°. As the diameter (or the length) of the projectile 100 increases, the difference between the groove angle θg and the tail angle θt decreases, and a difference between the length Lt and the length Lg increases.

The groove 132 may extend on the same imaginary line serving as a center line CL (that is, an axis) of the projectile 100 or may extend with an angle θa relative to the center line CL of the projectile 100 (hereinafter referred to as an “axis angle”) as illustrated in FIG. 7. The axis angle θa of the groove 132 indicates an angle of an axial line passing the center point Puc of the upstream part 132 a and the center point of Pdc of the downstream part 132 b relative to the center line CL of the projectile 100. The axis angle θa is in a range of preferably −15° to +30°, and more preferably −4° to +10°. Here, a minus sign “−’ indicates a left direction centering on the center line of the projectile 100, and a plus sign “+” indicates a right direction centering on the center line of the projectile 100.

To cause the project 100 to be expelled from the muzzle and reach a desired distance, pressure of the propellant may push a certain area or more of the bottom of the projectile 100 when the projectile 100 is fired. In other words, the bottom of the projectile 100 has a certain area or more. The grooves 132 are formed so that the desired area is provided in the bottom of the projectile 100. The bottom area is preferably ½ to ⅔ of an area of a projectile having no groove. In other words, the width and the depth of the groove 132 and the number of the grooves 132 are arranged so that, in an example, ½ to ⅔ of the area of the bottom of the projectile 100 remains. In the example of FIG. 7, the three grooves 132 are formed so that ½ to ⅔ of the area of the bottom of the projectile 100 remains relative to the area without the grooves.

The projectile of the related art suffers from an irregular air flow such as a vortex occurring behind the tail portion, and the flying force of the projectile is reduced accordingly.

However, since the projectile 100 according to the present embodiment includes a plurality of grooves 132 with the above-described structure, the air flows into the bottom of the projectile 100 along the grooves, and the irregular air flow such as the vortex does not occur or is reduced. Thus, the projectile 100 stably flies toward the target with a small yaw angle, and the effective range, the accuracy of hitting, and the destructive power of the projectile 100 are remarkably increased. In addition, since the gas may be uniformly discharged at the early stage, the recoil is reduced.

With reference to FIG. 8, without the grooves 132, the center of pressure (CP) is at a relative front position, and the center of gravity (CG) is at a relative rear position. Since the length of the projectile varies depending on the use purpose of the projectile, as the length of the projectile increases, the distance between the center of pressure (CP) and the center of gravity (CP) increases. As the distance between the center of pressure (CP) and the center of gravity (CP) increases, the yaw angle increases. The projectile expelled from the muzzle undergoes the spin precession maneuver (SPM) in which the projectile spins on the axis (e.g., the center line) thereof with the yaw angle. The spin precession maneuver (SPM) with the large yaw angle reduces the effective range, the accuracy of hitting, and the destructive power of the projectile. If the projectile rotates 180° in the traveling direction, and the tail portion of the projectile is positioned at front while giving little impact to the target as illustrated in FIG. 9A.

In this regard, the projectile of the present embodiment has a center of gravity (CG) close to the center of pressure (CP), as illustrated in FIG. 10.

FIG. 11 is a diagram illustrating an internal configuration of the projectile 100 according to the present embodiment. The projectile 100 includes a plurality of cores. Here, for the sake of simplicity of description, the projectile 100 is illustrated with first and second cores 140 and 150. In the example of FIG. 11, a jacket is not separately formed, and the outer surfaces of the first and second cores 140 and 150 serve as the jacket. However, the first and second cores 140 and 150 may be enveloped by a jacket 160 made of, for example, copper as illustrated in FIG. 12.

In the projectile 100 according to the present embodiment, the center of gravity (CG) of the projectile 100 is positioned between a middle point of the projectile 100 (a position corresponding to ½ of the length L of the projectile 100) and the center of pressure (CP). Accordingly, the yaw angle of the projectile 100 is reduced, and the effective range, the accuracy of hitting, and the destructive power of the projectile are significantly improved as illustrated in FIG. 9B.

The first and second cores 140 and 150 may be made of materials which cause the center of gravity (CG) of the projectile 100 to be positioned between the middle point of the projectile 100 and the center of pressure (CP). As the distance between the center of gravity (CG) and the center of pressure (CP) of the projectile 100 decreases, the yaw angle decreases, and the improvement in the effective range, the accuracy of hitting, and the destructive power of the projectile increases.

If the length of the first core 140 is indicated by Lc1, and the length of the second core 150 is indicated by Lc2, in the present embodiment, preferably, the first core 140 and the second core 150 have the length Lc1 and the length Lc2, respectively:

Lc1=L/5 to (3×L)/4

Lc2=L/4 to (4×L)/5,

where L indicates the length of the projectile 100.

In the present embodiment, the number of cores included in the projectile is two, but the number of cores is not particularly limited as long as the center of gravity (CG) of the projectile 100 is positioned between the middle point of the projectile 100 and the center of pressure (CP). For example, the number of cores may be one. In other word, the projectile 100 may have a single core in which the first core 140 and the second core 150 are integrally formed. The first and second cores 140 and 150 can be formed in various shapes as illustrated in FIGS. 13 and 14. FIG. 13 are diagrams illustrating examples in which the first and second cores 140 and 150 are separately formed, and FIG. 14 are diagrams illustrating examples in which the second core 150 is formed integrally with the first core 140 or the jacket 160.

The first core 140 may be made of a material which is higher in a specific gravity than the second core 150. In this case, the first core 140 is made of metal or a non-metal material, for example, one or more of an iron (Fe)-carbon (C)-based alloy, a tungsten carbide (WC)-based alloy, alloy steel, an aluminum (Al)-based alloy, copper (Cu), a Cu-based alloy, stainless steel, cast iron, a tungsten (W)-based alloy, chromium (Cr) steel, a molybdenum (Mo)-based alloy, an Ni—Cr—Mo-based alloy, a uranium (U)-based alloy, a 5Cr—Mo—V-based alloy, and a 5Ni—Cr—Mo—V-based alloy. The second core 150 is made of metal or a non-metal material, for example, one or more of an Al-based alloy, stainless steel, carbon (C), reinforced plastics, reinforced resin, non-ferrous metal, and an acrylonitrile butadiene styrene (ABS) material.

The first core 140 and the second core 150 may be made of the same material, for example, one or more of an iron (Fe)-carbon (C)-based alloy, a tungsten carbide (WC)-based alloy, alloy steel, an aluminum (Al)-based alloy, copper (Cu), a Cu-based alloy, stainless steel, cast iron, a tungsten (W)-based alloy, chromium (Cr) steel, a molybdenum (Mo)-based alloy, an Ni—Cr—Mo-based alloy, a uranium (U)-based alloy, a 5Cr—Mo—V-based alloy, and a 5Ni—Cr—Mo—V-based alloy, reinforced plastics, reinforced resin, non-ferrous metal, and an acrylonitrile butadiene styrene (ABS) material. In this case, the shapes of the first core 140 and the second core 150 are decided so that the center of gravity (CG) of the projectile 100 is positioned between the middle point of the projectile 100 and the center of pressure (CP).

In a case in which the jacket 160 is formed, the jacket 160 may be made of a soft material which is equal or lower in a specific gravity to or than the first core 140, for example, one or more of copper (Cu), a Cu-based alloy, and an Al-based alloy.

The center of gravity (CG) of the projectile 100 can be positioned between the middle point and the center of pressure (CP) of the projectile 100 by selecting materials for the first and second cores 140 and 150 and adjusting the specific gravities or the shapes of the first and second cores 140 and 150 in accordance with the position of the center of pressure (CP). The position of the center of pressure (CP) varies depending on the shape of the head portion 110 of the projectile 100, the length 100 of the projectile 100, or the like. The position of the center of pressure (CP) can be calculated using various methods.

For example, for projectiles having an ellipsoid head portion, the position of the center of pressure (CP) can be calculated using the following Formula (2):

CP=0.333×D,  (2)

where D indicates the diameter of the projectile.

For projectiles having an paraboloid head portion, the position of the center of pressure (CP) can be calculated using the following Formula (3)

CP=0.466×D,  (3)

where D indicates the diameter of the projectile.

In other words, in the present embodiment, for projectiles having an ellipsoid head portion, the center of gravity (CG) is preferably positioned within a range of 0.333×D to ½ from the terminal end of the head portion, and for projectiles having an paraboloid head portion, the center of gravity (CG) is positioned within a range of 0.466×D to ½ from the terminal end of the head portion.

FIG. 15A is a diagram illustrating an example of the second core 150 according to the present embodiment. As illustrated in FIG. 15A, the second core 150 may include a plurality of grooves 152 corresponding to the groove 130 illustrated in FIG. 1. The groove 152 is formed as a part of the groove 130 illustrated in FIG. 1. Thus, the cross-sectional shape, the depth, the groove angle, the groove width, and the like described above may be decided under the assumption that the groove 130 and the groove 152 constitute one groove. The groove 152 may have substantially the same axis angle as the groove 130 illustrated in FIG. 1.

FIG. 15B is a diagram illustrating another example of the second core 150 according to the present embodiment. As illustrated in FIG. 15B, the second core 150 according to the present embodiment may further include a plurality of recesses 154 which may be formed substantially in a straight line form. The stopping power may be increased by a plurality of recesses 154.

The first core 140 can be coupled with the second core 150 using various coupling techniques, and the present embodiment is not limited to a particular coupling technique. In examples of FIGS. 11 and 12, the first core 140 includes a first coupling portion 140 a, and the second core 150 includes a second coupling portion 150 a. The first core 140 may be coupled with the second core 150 such that the first coupling portion 140 a of the first core 140 is inserted into the second coupling portion 150 a of the second core 150. The first coupling portion 140 a may include a male screw portion, and the second coupling portion 150 a may include a female screw hole.

As described above, in the projectile 100 according to the present embodiment, the center of gravity (CG) of the projectile 100 is preferably positioned between the middle point and the center of pressure (CP) of the projectile 100 by selecting materials for the first and second cores 140 and 150 and adjusting the specific gravities or the shapes of the first and second cores 140 and 150 in accordance with the position of the center of pressure (CP). Accordingly, the yaw angle decreases, and the effective range, the accuracy of hitting, and the destructive power of the projectile are significantly improved.

A ballistics test was conducted on the projectile 100 according to the present embodiment. As a comparative example, Federal American Eagle M855 (5.56 mm) (hereinafter referred to as “M855”) was used. The length of the projectile was 23.3 mm, the weight was 4.01 g, an amount of propellant was 27.21 grains, the core was made of Cu and Pb, and the length of the boat tail was 2.5 mm. As an example of the projectile 100 of the present embodiment, the length of the projectile 100 was 23.5 mm, the weight was 2.89 g, an amount of propellant was 27.00 grain, the first core was made of Cu, the second core was made of Pb, the length of the boat tail was 9.8 mm, the axis angle was +1°, θt was 8.42°, θg was 20.56, and three grooves were formed.

In the accuracy test, the measurement was performed at a distance of 50 m, and the projectile of the present embodiment was five times higher in a degree of concentration than M855.

In the penetration test, both the projectile 100 of the present embodiment and M855 penetrated 6.8 mm soft steel plates at distances of 50 m to 200 m. The yaw phenomenon was remarkably shown in M855, but the projectile 100 of the present embodiment penetrated with little yaw angle. Although the weight of the projectile 100 of the present embodiment was much smaller than that of M855, the projectile 100 of the present embodiment showed almost the same level of destructive power as M855.

In the stopping power test, three 15 cm×15 cm ballistic gelatin tubes were used as a testing medium. M855 showed the effective stopping power up to the distance of 22 cm, but the projectile 100 of the present embodiment showed the effective stopping power up to the distance of 35 cm.

In the effective range test, a simulation was performed, and as a result of simulation, the effective range of the projectile 100 of the present embodiment was 800 m, whereas the effective range of M855 was 600 m.

As described above, according to the first embodiment, it is possible to provide a lightweight projectile capable of implementing the long effective range, the high accuracy of hitting, and the strong destructive power of the projectile.

Next, a projectile according to a second embodiment will be described. FIG. 16 is a diagram illustrating a projectile 200 according to a second embodiment of the present disclosure. In the second embodiment, the same reference numerals as in the first embodiment denote the same parts.

The projectile 200 of the present embodiment is a projectile with attributes advantageous for use underwater (hereinafter referred to as an “underwater projectile”). However, it will be understood that the projectile is not limited to underwater use. The projectile 200 of the present embodiment includes a head portion 210, a middle portion 220, and a tail portion 230. The middle portion 120 of the first embodiment may be employed as the middle portion 220, and the tail portion 130 of the first embodiment may be employed as the tail portion 230. In other words, the tail portion 230 may have a plurality of grooves 132 described above or may not include a plurality of grooves 132 described above.

The projectile 200 of the present embodiment may have the internal configuration of the first embodiment. In this case, the projectile 200 of the present embodiment may have the internal configuration in which the center of gravity (CP) is positioned between the middle point of the projectile 200 and the center of pressure (CP).

In the present embodiment, the projectile 200 may employ the tail portion 130 and the internal configuration which have been described in the first embodiment as the tail portion 230 and the internal configuration thereof. Since the tail portion 130 and the internal configuration have been described above, description thereof is omitted.

The projectile 200 of the second embodiment differs from the projectile 100 of the first embodiment in the head portion 210. The head portion 210 includes one or more supercavitating parts. The projectile 200 of the present embodiment will be described as including two or more supercavitating parts, but the number of supercavitating parts is not particularly limited. Even in the projectile 200 of the present embodiment including only one supercavitating part, the effective range of the projectile 200 is improved, and when the projectile 200 of the present embodiment includes two or more supercavitating part, the effective range of the projectile 200 is increased accordingly.

As illustrated in FIG. 17, the head part 210 of the projectile 200 of the present embodiment includes a first supercavitating part 210 a, a second supercavitating part 210 b, and an curved part 210 c. When a bullet is fired into water, the bullet experiences big impact and may be mostly deformed. For this reason, the head part 210 is preferably made of a material capable of penetrating the water while resisting the big impact without being deformed. For example, the head part 210 is preferably made of a tungsten carbide (WC)-based alloy.

The first supercavitating part 210 a performs a first supercavitation effect of creating a bubble of gas (a supercavity) underwater large enough to encompass the projectile 200 as illustrated in FIG. 18A.

The first supercavitating part 210 a includes a tip 210 a-1 and a first inwardly recessed part 210 a-2. The tip 210 a-1 may have a substantially a semi-spherical shape. However, the tip 210 a-1 can have various shapes. For example, the top 210 a-1 may have a pointed shape, a semi-elliptical shape, a semi-oval shape, or a polygonal shape. The first inwardly recessed part 210 a-2 has an inwardly rounded shape or a concave shape. The pressure of water is suddenly lowered in the first inwardly recessed part 210 a-2, so that the supercavity is formed large enough to encompass the projectile 200. Since the supercavitation effect is created, the effective range of the projectile 200 is increased remarkably.

In a case in which the tip 210 a-1 has a semi-spherical shape, preferably, a radius value Rt of the tip 210 a-1 is ⅕ to ⅓ of a radius value Rr1 of the first inwardly recessed part 210 a-2. In a case in which the first inwardly recessed part 210 a-2 has an inwardly rounded shape, preferably, the radius value Rr1 of the inwardly recessed part 210 a-2 is 1/10 to 4/10 of the diameter L of the projectile 200.

The second supercavitating part 210 b performs a second supercavitation effect of creating a bubble of gas (a supercavity) underwater large enough to encompass the remaining part of the projectile 200 when the velocity of the projectile 200 is reduced, and the water just comes into contact with the second supercavitating part 210 b as illustrated in FIG. 17B.

The second supercavitating part 210 b includes an upwardly oblique part 210 b-1 and a second inwardly recessed part 210 b-2. The upwardly oblique part 210 b-1 has an angle θa11. The second inwardly recessed part 210 b-2 has an inwardly rounded shape or a concave shape. The second inwardly recessed part 210 b-2 has an angle θr11 larger than the angle θa11. The second inwardly recessed part 210 b-2 may be replaced with an upwardly oblique part having the angle θr11 larger than the angle θa11.

Preferably, the angle θa11 of the upwardly oblique part 210 b-1 is 5° to 15°, and preferably, the angle θr11 of the second inwardly recessed part 210 b-2 is equal to the angle θa11. In a case in which the second inwardly recessed part 210 b-2 has an inwardly rounded shape, preferably, a radius value Rr2 of the second inwardly recessed part 210 b-2 is equal to the radius value Rr1 of the first inwardly recessed part 210 a-2.

The curved part 210 c may be similar to a corresponding part of a common projectile.

As described above, since the projectile 200 of the present embodiment includes the first supercavitating part 210 a and the second supercavitating part 210 b, the supercavitation is performed twice, and the effective range of the projectile 200 is increased accordingly.

FIG. 19 is a diagram illustrating a projectile 300 according to a first modified example of the second embodiment. The projectile 300 of the present modified example includes a first supercavitating part 310 a, a second supercavitating part 310 b, and an curved part 310 c.

The first supercavitating part 310 a performs a first supercavitation effect of creating a bubble of gas (a supercavity) underwater large enough to encompass the projectile 300.

The first supercavitating part 310 a includes a tip 310 a-1, a first upwardly oblique part 310 a-2, and a first inwardly recessed part 310 a-3. The tip 310 a-1 is similar to the tip 210 a-1, the description of FIG. 17 can be applied to the tip 310 a-1, and thus description thereof is omitted. The first upwardly oblique part 310 a-2 has an angle θa21. The first inwardly recessed part 310 a-3 has an inwardly rounded shape or a concave shape. The first inwardly recessed part 310 a-3 has an angle θr21 larger than the angle θa21. The first inwardly recessed part 310 a-3 may be replaced with an upwardly oblique part having the angle θr21 larger than the angle θa21.

The second supercavitating part 310 b performs a second supercavitation effect of creating a bubble of gas (a supercavity) underwater large enough to encompass the remaining part of the projectile 300 when the velocity of the projectile 200 is reduced, and the water just comes into contact with the second supercavitating part 310 b.

The second supercavitating part 310 b includes a second upwardly oblique part 310 b-1, a third upwardly oblique part 310 b-2, and a fourth upwardly oblique part 310 b-3. Preferably, an angle θa22 of the second upwardly oblique part 310 b-1, an angle θa23 of the third upwardly oblique part 310 b-2, and an angle θa24 of the fourth upwardly oblique part 310 b-3 are different from one another and have a relation of θa22<θa23<θa24.

Here, preferably, an angle θsc11 formed by the first upwardly oblique part 310 a-2 and the first inwardly recessed part 310 a-3 is substantially equal to an angle θsc12 formed by the third upwardly oblique part 310 b-2 and the fourth upwardly oblique part 310 b-3.

The curved part 310 c may be similar to a corresponding part of a common projectile.

As described above, since the projectile 300 of the present embodiment includes the first supercavitating part 310 a and the second supercavitating part 310 b, the supercavitation is performed twice, and the effective range of the projectile 300 is increased accordingly.

FIG. 20 is a diagram illustrating a projectile 400 according to a second modified example of the second embodiment. The projectile 400 of the present modified example includes a first supercavitating part 410 a, a second supercavitating part 410 b, a third supercavitating part 410 c, and a curved part 410 d.

The first supercavitating part 410 a performs a first supercavitation effect of creating a bubble of gas (a supercavity) underwater large enough to encompass the projectile 400.

The first supercavitating part 410 a includes a tip 410 a-1, a first upwardly oblique part 410 a-2, a second upwardly oblique part 410 a-3, and a third upwardly oblique part 410 a-4. The tip 410 a-1 is similar to the tip 410 a-1, the description of FIG. 17 can applied to the tip 410 a-1, and thus description thereof is omitted.

Preferably, an angle θa31 of the first upwardly oblique part 410 a-1, an angle θa32 of the second upwardly oblique part 410 a-2, and an angle θa33 of the third upwardly oblique part 410 a-3 are different from one another and have a relation of θa31<θa32<θa33.

The second supercavitating part 410 b performs a second supercavitation effect of creating a bubble of gas (a supercavity) underwater large enough to encompass the remaining part of the projectile 400 when the velocity of the projectile 400 is reduced, and the water just comes into contact with the second supercavitating part 410 b.

The second supercavitating part 410 b includes a fourth upwardly oblique part 410 b-1 and a first inwardly recessed part 410 b-2. The fourth upwardly oblique part 410 b-1 has an angle θa34. The first inwardly recessed part 410 b-2 has an inwardly rounded shape or a concave shape. The first inwardly recessed part 410 b-2 has an angle θr31 larger than the angle θa34. The first inwardly recessed part 410 b-2 may be replaced with an upwardly oblique part having the angle θr31 larger than the angle θa34.

The third supercavitating part 410 c forms a third supercavitation effect of creating a bubble of gas (a supercavity) underwater large enough to encompass the remaining part of the projectile 400 when the velocity of the projectile 400 is reduced, and the water just comes into contact with the second supercavitating part 410 c.

The third supercavitating part 410 c includes a fifth upwardly oblique part 410 c-1 and a second inwardly recessed part 410 c-2. The fifth upwardly oblique part 410 c-1 has an angle θa35. The second inwardly recessed part 410 c-2 has an inwardly rounded shape or a concave shape. The second inwardly recessed part 410 c-2 has an angle θr32 larger than the angle θa35. The second inwardly recessed part 410 c-2 may be replaced with an upwardly oblique part having the angle θr32 larger than the angle θa35.

Here, preferably, an angle θsc21 formed by the first upwardly oblique part 410 a-2, the second upwardly oblique part 410 a-3, and the third upwardly oblique part 410 a-4, an angle θsc22 formed by the fourth upwardly oblique part 410 b-1 and the first inwardly recessed part 410 b-2, and an angle θsc23 formed by the fifth upwardly oblique part 410 c-1 and the second inwardly recessed part 410 c-2 are substantially equal.

If an imaginary circle is formed by connecting points p11, p12, and p13, preferably, a radius value Rr2 of the circle is substantially equal to the radius value Rr1 of the first inwardly recessed part 210 a-2 of FIG. 17. Further, if an imaginary circle is formed by connecting points p11, p21, and p22, preferably, a radius value Rr3 of the circle is preferably substantially equal to the radius value Rr1 of the first inwardly recessed part 210 a-2 of FIG. 16.

In the second modified example of the second embodiment, since the projectile 400 of the present embodiment includes the first supercavitating part 410 a, the second supercavitating part 410 b, and the third supercavitating part 410 c, the supercavitation is performed three times, and the effective range of the projectile 400 is increased accordingly.

In the case of the underwater projectile moving underwater, when a certain length or more comes into contact with the water, the underwater projectile is unable to move forward any more. The supercavity formed by the supercavitation to encompass the projectile depends on the diameter of the projectile.

FIG. 21 is a diagram with exemplary dimensions of the head portion of the underwater projectile according to the present embodiment. As described above, the underwater projectile according to the present embodiment can have at least one supercavitating part, and the number of supercavitating parts is not particularly limited.

For advantageous supercavitation, preferably, the supercavitating parts are formed within a range of L/3 or less in a longitudinal direction and a range of D×0.85 or less in a diameter direction (here, D is the diameter of the projectile). A height Q added when the second supercavitating part is added is at least ¼ of Dsc1 (Here, Dsc1 indicates a diameter of the first supercavitating part), and a height added when the third supercavitating part is added is at least ¼ of Dsc2 (Here, Dsc2 indicates a diameter of the second supercavitating part). In other words, the diameter Dsc2 of the second supercavitating part is at least 1.25×Dsc1, and the diameter Dsc3 of the third supercavitating part is at least 1.25×Dsc2. As described above, each time the supercavitating part is added, the diameter of the supercavitating part may be increased by about 25%. The diameter Dsc1 of the first supercavitating part can be obtained using the radius value Rr1 of the first inwardly recessed part 210 a-2.

As described above, the supercavitating parts can be formed using a combination of an upwardly oblique part and an inwardly recessed part having different angles. The number of supercavitating parts is not limited and preferably they are formed within the range of L/3 or less in the longitudinal direction and the range of D×0.85 or less in the diameter direction.

According to the second embodiment of the present disclosure, the effective range, the accuracy of hitting, and the destructive power of the underwater projectile are significantly improved. In addition, the projectile according to the second embodiment of the present disclosure can work in air as well as underwater and thus work from air to water and from water to air.

The present disclosure can be applied to projectiles having an explosive installed therein such as may be used in artillery weapons such as cannons, howitzers, mortars, large guns, and the like installed in tanks, fighters, battleships, or submarines (hereinafter referred to as an “artillery projectile”).

FIG. 22 is a diagram illustrating an example of an artillery projectile 500 according to a third embodiment of the present disclosure. The projectile 500 according to the third embodiment of the present disclosure differs from the projectiles of the first and second embodiments in that an explosive is installed. In other words, the projectile 500 of the third embodiment may include the tail portion 130 including a plurality of grooves 132 described above and/or the internal configuration in which the center of gravity (CG) is positioned between the middle point and the center of pressure (CP) of the projectile 100. The projectile 500 of the third embodiment may include the head portion having the supercavitating part described in the second embodiment. Since the tail portion 130 including a plurality of grooves 132 described above, the internal configuration in which the center of gravity (CG) is positioned between the middle point and the center of pressure (CP) of the projectile 100, and the head portion having the supercavitating part have been described above, description thereof is omitted.

In FIG. 22, reference numeral 510 indicates a fuse, 520 indicates a front jacket including a core, 530 indicates an inner filler, 540 indicates a rear jacket, and 550 indicates a TNT filler serving as an explosive.

The artillery projectile 500 illustrated in FIG. 22 is merely an example, and the present disclosure can be applied to artillery projectiles having different types of explosion structures or explosives.

According to the third embodiment of the present disclosure, the effective range, the accuracy of hitting, and the destructive power of the artillery projectile are significantly improved.

As described above, according to the present disclosure, it is possible to provide the lightweight projectile capable of implementing the long effective range, the high accuracy of hitting, and the strong destructive power of the projectile.

Preferred exemplary embodiments of the present disclosure are described for illustrative purposes, and the scope of the present disclosure is not limited to the above described specific examples. It will be apparent to those skilled in the art that various variations and modifications may be made without departing from the spirit and scope of the disclosure as defined in the following claims. 

What is claimed is:
 1. A projectile, comprising: a head portion; a tail portion; and a middle portion disposed between the head portion and the tail portion, wherein an area of a terminal end of the tail portion is in the range of ½ to ⅔ of an area of a circle having a diameter the same as a diameter of the terminal end of the tail portion.
 2. The projectile of claim 1, wherein a recess is defined from a terminal end of the tail portion and extending into the middle portion, and a length that the recess extends into the middle portion is in the range of L/11 to L/22 where L is a length of the projectile.
 3. The projectile of claim 2, wherein a length of the recess is in the range of (L/8 to L/2)+(L/11 to L/22).
 4. The projectile of claim 1, wherein a length of the tail portion is in the range of L/8 to L/2 where L is a length of the projectile.
 5. The projectile of claim 1, wherein a recess is defined from a terminal end of the tail portion and extending toward the middle portion, and an angle of an axis of the recess relative to a center line of the projectile is in the range of −15° to +30°.
 6. The projectile of claim 5, wherein the angle of the axis of the recess relative to the center line of the projectile is in the range of −4° to +10°.
 7. The projectile of claim 1, wherein a recess is defined from a terminal end of the tail portion and extending toward the middle portion, an outer surface of the tail portion forms a first angle relative to a center line of the projectile, a surface of the recess forms a second angle relative to the center line of the projectile, and a difference between the first angle and the second angle is in the range of 5° to 30°.
 8. The projectile of claim 7, wherein the difference between the first angle and the second angle is in the range of 10° to 20°.
 9. The projectile of claim 1, wherein the head portion includes a first region having a concave profile.
 10. The projectile of claim 9, wherein the head portion includes a second region having a concave profile disposed between the first region and the middle portion.
 11. A projectile, comprising: a head portion; a tail portion; and a middle portion disposed between the head portion and the tail portion, wherein a center of gravity of the projectile is disposed between a midpoint of the projectile and a terminal end of the head portion.
 12. The projectile of claim 11, wherein the projectile includes a first core and a second core.
 13. The projectile of claim 12, wherein a length of the first core is in the range of L/5 to 3*L/4 where L is a length of the projectile.
 14. The projectile of claim 12, wherein a length of the second core is in the range of L/4 to 4*L/5 where L is a length of the projectile.
 15. The projectile of claim 12, wherein a material of the first core and a material of the second core are different.
 16. The projectile of claim 12, wherein at least one of a material of the first core and a material of the second core is non-metallic.
 17. The projectile of claim 11, wherein one or more recesses are respectively defined from a terminal end of the tail portion and extending toward the middle portion, and an area of the terminal end of the tail portion is in the range of ½ to ⅔ of an area of a circle having a diameter the same as a diameter of the terminal end of the tail portion.
 18. The projectile of claim 11, wherein the head portion includes a first region having a concave profile.
 19. The projectile of claim 11, wherein one or more recesses are respectively defined from a terminal end of the tail portion and extending toward the middle portion, and an angle of an axis of the recess relative to a center line of the projectile is in the range of −15° to +30°.
 20. The projectile of claim 19, wherein the angle of the axis of the recess relative to the center line of the projectile is in the range of −4° to +10°. 